Liquid flow measurement device based on HFD and TDP dual modes and its measurement method

Abstract

The present invention relates to a liquid flow measuring device based on HFD and TDP dual modes and a measuring method thereof, the device comprising: a sensing component, comprising a first temperature measuring probe, a second temperature measuring probe, a third temperature measuring probe and a fourth temperature measuring probe arranged in a tree trunk, wherein the first temperature measuring probe, the second temperature measuring probe, the third temperature measuring probe and the fourth temperature measuring probe are arranged in sequence from top to bottom along the extension direction of the tree trunk; a heating device, comprising a heating probe arranged in the tree trunk, the heating probe and the second temperature measuring probe are located at the same height of the tree trunk; a data acquisition controller, for controlling each temperature measuring probe of the sensing component to collect temperature data, and controlling the heating probe to heat. The present invention combines the respective advantages of the HFD and TDP methods, and can be used to replace the traditional commonly used thermal diffusion probe, improve the validity and accuracy of the measurement data, and reduce data redundancy.

Description

Technical Field

[0001] The present invention relates to a liquid flow measuring device and a measuring method thereof based on the dual modes of HFD (thermal field deformation method) and TDP (thermal diffusion method), and relates to the technical field of forest liquid flow measurement. Background Art

[0002] The sap flow method based on thermal technology has many advantages, such as low cost, easy implementation, and the ability to help understand and reveal more detailed plant physiological and ecological processes and mechanisms. It has become the mainstream method for estimating forest transpiration at the scale of individual trees and forest stands. According to different measurement principles, the sap flow method can be divided into three categories: thermal pulse method, thermal diffusion method, and thermal field deformation method.

[0003] Heat Field Deformation (HFD) is a liquid flow measurement technology based on continuous heating. The heating probe continuously releases heat and forms a stable thermal field, which deforms as the liquid flow density changes. The thermal field deformation sensor is based on the principle of calculating the radial thermal field deformation around the linear heating needle, so as to accurately calculate the liquid flow density. Compared with other measurement methods, HFD technology can achieve multi-site measurements at different depths with high time resolution, and has the advantages of accurately measuring high, low, zero liquid flow and reverse liquid flow. The existing HFD products and data analysis software are expensive, which limits the promotion and application of this technology.

[0004] The Thermal Dissipation Probes (TDP) method was proposed by André Granier of the French National Academy of Agricultural Sciences and is currently the most widely used method for measuring sap flow. The measurement principle is to insert a probe with a built-in heating wire and a temperature sensor into the wood with water conduction function, and then apply a constant voltage to the heating wire to continuously supply heat. When the thermal equilibrium state, i.e., steady state, is finally reached, the sap flow density is calculated based on the temperature difference between the two probes. The current TDP measurement of sap flow is affected by a variety of error sources, such as radial variation and circumferential variation of sap flow density. Among them, since the thermal diffusion method calculates sap flow density based on an empirical model, it is difficult to accurately measure low sap flow and reverse sap flow, and due to the influence of differences in wood properties between different tree species, there may be large differences in the calculation of sap flow using a unified empirical formula. These problems reduce the accuracy of forest sap flow measurement and cause greater deviations in further estimating forest water consumption.

[0005] Therefore, it is urgent to design a new type of forest sap flow measurement device to break through the technical bottleneck of using thermal technology methods to achieve accurate estimation of forest water consumption. Summary of the invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, in view of the above problems, the purpose of the present invention is to provide a high-precision, multi-point and bidirectional liquid flow detection device based on HFD and TDP dual modes and a measurement method thereof.

[0007] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is:

[0008] In a first aspect, the present invention provides a liquid flow measurement device based on HFD and TDP dual modes, the device comprising:

[0009] The sensing assembly comprises a first temperature measuring probe, a second temperature measuring probe, a third temperature measuring probe and a fourth temperature measuring probe arranged in a tree trunk, wherein the first temperature measuring probe, the second temperature measuring probe, the third temperature measuring probe and the fourth temperature measuring probe are arranged in sequence from top to bottom along the extension direction of the tree trunk;

[0010] The heating device comprises a heating probe arranged in the trunk of the forest tree, wherein the heating probe and the second temperature measuring probe are located at the same height of the trunk of the forest tree;

[0011] The data acquisition controller is used to control each temperature measuring probe of the sensing assembly to collect temperature data and control the heating probe to perform heating.

[0012] In some embodiments, the first temperature measuring probe, the second temperature measuring probe, the third temperature measuring probe and the fourth temperature measuring probe are arranged at non-uniform intervals from top to bottom along the extension direction of the tree trunks, wherein the first temperature measuring probe and the third temperature measuring probe are symmetrically arranged based on the heating probe.

[0013] In some embodiments, the longitudinal spacing between the first temperature measuring probe, the heating probe and the third temperature measuring probe is 15 mm; the lateral spacing between the heating probe and the second temperature measuring probe is 5 mm; and the longitudinal spacing between the third temperature measuring probe and the fourth temperature measuring probe is 25 mm.

[0014] In some embodiments, each temperature measuring probe in the sensing assembly uses a T-type thermistor wire, and each of the temperature measuring probes includes a plurality of T-type thermocouple wires for multi-point measurement.

[0015] In some embodiments, the total length of each temperature measuring probe is N=x+n*i, wherein x is the distance between the outermost measuring point and the needle seat, n is the distance between each micro-thermocouple, and i is the number of thermocouples.

[0016] In some embodiments, a heating resistor is provided in the heating probe. The heating resistor is made of resistance wire of various materials, including constantan wire, tungsten wire, chromium wire or nickel wire. The heating power of the heating resistor is 0.06-0.08w / cm, and the actual length of the heating resistor is consistent with the required resistivity of the probe.

[0017] In some embodiments, each of the probes includes an elongated probe body, and the heating resistor is disposed along the length direction of the probe body.

[0018] In a second aspect, the present invention further provides a measurement method of the liquid flow measurement device based on the HFD and TDP dual modes according to the first invention of the present invention, comprising:

[0019] Determine the location of the sensor components and heating devices for the tree species;

[0020] Install the sensor assembly and the heating device at the installation location selected by the tree species;

[0021] A constant voltage is applied to the forest tree species through the heating device to continuously supply heat. When the thermal equilibrium state, i.e. the steady state, is finally reached, the liquid flow density is calculated based on the temperature difference between the probes.

[0022] In some embodiments, the liquid flux density q is calculated based on the temperature difference between the probes based on the thermal field deformation method. s :

[0023]

[0024] Where D is the thermal diffusivity of wood, K is the "asymmetric point temperature difference" when there is zero liquid flow, and dT as is the temperature difference between the second temperature measuring probe and the third temperature measuring probe, dT sym is the “symmetric point temperature difference”, i.e. the temperature difference between the first temperature measuring probe and the third temperature measuring probe; Z ax is the distance between the heating probe and the first and third temperature measuring probes, Z tg is the distance between the heating probe and the second temperature measuring probe, L sw is the sapwood thickness of the measured plant.

[0025] In some embodiments, the liquid flux density F is calculated based on the temperature difference between the probes based on the thermal diffusion method. d :

[0026] F d =a·K b Where, K is the temperature difference coefficient, K = (Δ TM -Δ T ) / Δ T , Δ TMThe temperature difference between the heating temperature set by the heating probe and the fourth temperature measuring probe when the liquid flow density is 0 cm / s; Δ T is the instantaneous temperature difference between the heating temperature set by the heating probe at a certain moment and the fourth temperature measuring probe; a and b are the coefficients of the Granier original formula respectively.

[0027] The present invention adopts the above technical solution, and has the following characteristics:

[0028] 1. The forest sap flow measuring device based on the dual modes of thermal field deformation method and thermal diffusion method provided by the present invention combines the respective advantages of HFD and TDP methods, can improve the validity and accuracy of measurement data, reduce data redundancy, and reduce energy consumption.

[0029] 2. The present invention combines the core principles and practical application advantages of the thermal field deformation method and the thermal diffusion method, and expands the single measurement point in the thermal diffusion probe into multiple points, which can be used to measure the liquid flow density in different radial directions of the tree trunk.

[0030] 3. Most of the sensors in traditional devices for measuring liquid flow density are of the "single-point two-needle type", which can only measure the forward liquid flow at a single point in the tree stem, but not the reverse liquid flow, and it is difficult to meet the research on the strategy mechanism of tree adaptation to water conditions. The measuring device proposed in the present invention adopts a "multi-site composite" sensor, and provides a dual-mode multi-site forest liquid flow measurement device based on the thermal field deformation method and the thermal diffusion method, which can measure both the forward liquid flow density and the reverse liquid flow density. The measurement data is highly accurate and can better characterize the water physiological ecology.

[0031] In summary, the present invention can be widely used in forest sap flow measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Throughout the accompanying drawings, the same reference numerals are used to represent the same components. In the accompanying drawings:

[0033] Figure 1 Schematic diagram of the structure of a liquid flow measuring device according to an embodiment of the present invention.

[0034] Figure 2 This is a schematic diagram of the structure and composition of a forest sap flow measurement probe based on a dual-mode thermal field deformation method and a thermal diffusion method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] It should be understood that the terms used herein are only for the purpose of describing specific example embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "include", "comprise", "contain", and "have" are inclusive, and therefore specify the existence of stated features, steps, operations, elements and / or parts, but do not exclude the existence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not interpreted as necessarily requiring them to be performed in the specific order described or illustrated, unless the execution order is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0036] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments.

[0037] For ease of description, spatially relative terms may be used herein to describe the relationship of one element or feature relative to another element or feature as shown in the figures, such as "inside", "outside", "inner side", "outer side", "below", "above", etc. Such spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figures.

[0038] Since it is urgent to design a new type of forest sap flow measuring device to break through the technical bottleneck of using thermal technology to achieve accurate estimation of forest water consumption. The sap flow measuring device based on HFD and TDP dual modes and its measurement method provided by the present invention include: a sensing component, including a first temperature measuring probe, a second temperature measuring probe, a third temperature measuring probe and a fourth temperature measuring probe arranged in the trunk of the forest, wherein the first temperature measuring probe, the second temperature measuring probe, the third temperature measuring probe and the fourth temperature measuring probe are arranged in sequence from top to bottom along the extension direction of the trunk of the forest; a heating device, including a heating probe arranged in the trunk of the forest, and the heating probe and the second temperature measuring probe are located at the same height of the trunk of the forest; a data acquisition controller, which is used to control each temperature measuring probe of the sensing component to collect temperature data, and control the heating probe to heat. Therefore, the present invention can be used to replace the traditional commonly used thermal diffusion probe, which can measure both the forward sap flow density and the reverse sap flow density, and the measurement data has high accuracy, which can better characterize the water physiological ecology.

[0039] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0040] Embodiment 1: Figure 1 As shown, the liquid flow measurement device based on the HFD and TDP dual modes provided in this embodiment includes a sensor component, a heating device, a data acquisition controller and a power supply device.

[0041] The sensing component includes a first temperature measuring probe 1, a second temperature measuring probe 2, a third temperature measuring probe 3 and a fourth temperature measuring probe 4 which are arranged at unequal intervals from top to bottom along the extension direction of the tree trunk (the top refers to the crown part and the bottom refers to the root part along the extension direction of the trunk), and each temperature measuring probe is provided with a temperature measuring component.

[0042] The heating device comprises a heating probe 5 arranged at the same height as the second temperature measuring probe 2 , wherein a heating component is arranged inside the heating probe 5 , wherein the first temperature measuring probe 1 and the third temperature measuring probe 4 are symmetrically arranged based on the heating probe 5 .

[0043] The data acquisition controller 6 is used to control the sensor component to collect temperature data and control the heating device to perform heating.

[0044] The power supply device 7 is used to supply power to various electrical devices.

[0045] In a preferred embodiment of the present invention, the outer shells of the sensor component and the heating device can be made of stainless steel, and the outer diameter of each probe can be set to 1.3 mm. This is taken as an example and is not limited to this. Therefore, by reducing the overall diameter of the probe, it is easy to insert it into the wood.

[0046] In a preferred embodiment of the present invention, the sensing component can be a T-type thermistor, which has the advantages of high sensitivity, good linearity, and convenient welding and manufacturing.

[0047] Furthermore, if Figure 2 As shown, the sensing component can be used to perform multi-point measurement including several, for example, 1-6 0.08 mm T-type thermocouple wires, wherein each micro thermocouple can be equidistantly distributed, and the distance can be selected to be 6-15 mm. This is taken as an example and is not limited to this.

[0048] Furthermore, the total length of each probe of the sensor assembly 1 (N) = x + n * i, wherein x is the distance between the outermost measuring point and the needle seat, n is the distance between each micro thermocouple, and i is the number of thermocouples.

[0049] Furthermore, the lengths of the first temperature measuring probe 1 , the second temperature measuring probe 2 and the third temperature measuring probe 3 can be set to be dual-site thermocouple probes of 44 mm; the fourth temperature measuring probe 4 can be a dual-site thermocouple probe of 22.5 mm in length, and this is taken as an example, but not limited to this.

[0050] In a preferred embodiment of the present invention, the spacing between each temperature measuring probe and each heating probe is 5-100 mm, and this is taken as an example but is not limited thereto.

[0051] Furthermore, the longitudinal spacing between the first temperature measuring probe 1, the heating probe 5, and the third temperature measuring probe 3 is 15 mm; the lateral spacing between the heating probe 5 and the second temperature measuring probe 2 is 5 mm; the longitudinal spacing between the third temperature measuring probe 3 and the fourth temperature measuring probe 4 is 25 mm. This is taken as an example and is not limited to this.

[0052] In a preferred embodiment of the present invention, the heating probe 5 comprises a linear heating probe having a length of 60 mm along the extending direction of the tree trunk, and this is taken as an example but not limited thereto.

[0053] Furthermore, the heating probe 5 may be a heating resistor, and the heating resistor may be a resistance wire of various materials, such as constantan wire, tungsten wire, chromium wire, nickel wire, etc. In this embodiment, the heating component uses constantan wire or tungsten wire, because these two metals have high resistivity, and under the condition that the resistance value of the heating resistor is the same, the length of the constantan wire or tungsten wire is shorter, which can greatly reduce the difficulty of the manufacturing process of integrating it into the probe.

[0054] Furthermore, the heating power of the heating component is 0.06-0.08w / cm, and the actual length of the heating component is consistent with the required resistivity of the probe.

[0055] Furthermore, each probe may include an elongated probe body; and the heating resistor is arranged along the length direction of the probe body.

[0056] In a preferred embodiment of the present invention, the data acquisition controller 6 can be fixed to the customized stainless steel bracket 8 by snapping, and the modules for collecting and storing the temperature data of the temperature measuring component and controlling the heating component to perform heating are all integrated in the data acquisition controller.

[0057] Furthermore, the power supply device 7 may be a solar panel disposed on the top of the stainless steel bracket 8 for supplying power to various electrical devices.

[0058] In summary, the working principle of the liquid flow measurement device based on the HFD and TDP dual modes provided in this embodiment is: the present invention is based on the thermal field deformation method technology, that is, the continuous heating sensor-heating probe continuously releases heat and forms a stable thermal field, which deforms as the liquid flow density changes. The thermal field deformation method sensor is based on the principle of calculating the radial thermal field deformation around the linear heating needle, so as to accurately calculate the liquid flow density. The present invention is also based on the thermal diffusion method, inserting the built-in heating wire and the temperature measuring probe into the wood with water conduction function, and then applying a constant voltage to the heating wire to continuously supply heat. When the thermal equilibrium state, that is, the steady state, is finally reached, the liquid flow density is calculated according to the temperature difference between the two temperature measuring probes. Compared with the measuring device and method in the prior art, the present invention can achieve high time resolution multi-site measurement at different depths, and has the advantages of accurately measuring high, low, zero liquid flow and reverse liquid flow. Combining the respective advantages of the HFD and TDP methods can improve the effectiveness and accuracy of measurement data, reduce data redundancy, reduce energy consumption, and realize data sharing on the cloud server platform, providing researchers with a method to remotely monitor the dynamics of tree trunk sap flow and predict sap flow trends, thereby scientifically managing forests and water-saving irrigation.

[0059] Embodiment 2: The measurement method of the forest sap flow measurement device based on the HFD and TDP dual modes provided in this embodiment includes the following steps:

[0060] S1. Obtain the sapwood depth, sapwood area, etc. of the observed tree species.

[0061] In this embodiment, the sapwood depth and sapwood area of ​​the observed tree species can be investigated and determined by drilling a wood core with a growth cone or simply estimating according to literature and empirical formulas. Only after the sapwood depth and sapwood area are accurately measured or estimated can the sap flux density, sap flux, etc. be accurately calculated.

[0062] S2. Determine the locations on the wood materials where the sensor components and heating devices are to be installed.

[0063] In this embodiment, the measurement of the three-dimensional thermal field based on the thermal field deformation method needs to avoid plant parts that may cause uneven thermal fields, such as branches and curved parts of trunks or branches and roots. The selected installation site should be relatively straight, and whether the bark in the installation area needs to be peeled off can be determined based on the bark thickness and sapwood depth.

[0064] S3. Install the sensor assembly and heating device at the selected installation location of the tree material

[0065] In this embodiment, when the probe is installed, the gap of the hole needs to match the diameter of the probe. Since the probe is relatively long, when the hole is punched too tightly, it will be difficult to insert and remove the probe, and may even cause the probe to break; when the hole is punched too loosely, the probe will not fit tightly with the wood, affecting the measurement precision and accuracy. Different tree species have different densities, so the hole diameters may differ to a certain extent. The customized diameter of the probe in this embodiment can be 1.3mm, but it is not limited to this size. Therefore, it is recommended to first use a slender twist drill bit of the same diameter to align with the drill template and drive it vertically into the tree body, and then insert the probe into the hole for trial. If the resistance is small, you can continue to use the drill bit to drill back and forth several times to expand the hole diameter in a small range. If the resistance is large, you need to replace a thicker drill bit to expand the hole diameter. When using a drill bit, only one in and out movement is required for the first time. Reciprocating in and out movement should be avoided (which may cause the hole diameter to be too large and thus not fit the probe well). Then try to insert the probe into the hole. If there is still great resistance and it is difficult to insert it completely, use a thicker drill bit to expand the hole again. At this time, reciprocating in and out movement should still be avoided until the probe can be smoothly and completely inserted into the hole under certain resistance.

[0066] S4. Constant voltage is applied to the wood through the heating device to continuously supply heat. When a thermal equilibrium state, i.e. a steady state, is finally reached, the liquid flow density is calculated based on the temperature difference between the probes.

[0067] In this embodiment, after the probe is inserted into the xylem of the plant, the heated probe continuously releases heat and forms a stable thermal field, which deforms as the liquid flow density changes. The HFD system measures the "symmetric point temperature difference" (dT sym , that is, the temperature difference between the first temperature measuring probe and the third temperature measuring probe) and the “asymmetric point temperature difference” (dT as , that is, the temperature difference between the second temperature measuring probe and the third temperature measuring probe) is collected to accurately calculate the liquid flow density.

[0068] In this example, according to Nadezhdina (2018), the liquid flux density q of the thermal field deformation method is s (cm / h) is calculated as follows:

[0069]

[0070] Where D is the thermal diffusivity of fresh wood, which is 0.0025 cm according to Marshall (1958). 2 s -1 , K is the "asymmetric point temperature difference" when the liquid flow is zero. ax is the distance between the heating probe 5 and the first temperature measuring probe 1 and the third temperature measuring probe 3 (15 mm), Z tg is the distance between the heating probe 5 and the second temperature measuring probe 2 (5 mm), L sw (cm) is the sapwood depth of the measured tree. After calculating the sap flux density, the sap flux can be obtained by multiplying it with the sapwood area.

[0071] Furthermore, the K value is the “asymmetric point temperature difference” (dT as ), which is an extremely important parameter and a necessary parameter for calculating liquid flow. It is generally necessary to calculate dT based on a certain time series (five to ten days). sym With dT as Data, through dT as With dT as / dT sym The relationship diagram of K value is used to determine the K value, including: when zero liquid flow or reverse liquid flow occurs (dT as / dT sym =0), the intercept of the scatter points on the y-axis is the K value; when there is no zero liquid flow and reverse liquid flow, there is no intersection on the y-axis of the scatter plot. At this time, the scatter points on the far left that are close to linear changes can be used for linear fitting, and the intercept of the fitting line on the y-axis is the K value.

[0072] In this embodiment, according to Granier (1985), the liquid flux density F of the thermal diffusion method is d (cm / s) is calculated as follows:

[0073] F d =a·K b ;

[0074] In the formula, the temperature difference coefficient K = (Δ TM -Δ T ) / Δ T , Δ TM is the temperature difference when the liquid flux density is 0 cm / s (℃); Δ T is the instantaneous temperature difference at a certain moment (℃); Granier original formula coefficient a is 0.0119, coefficient b is 1.231, among which, the original temperature difference obtained during measurement (Δ T ) is the temperature difference between the heating temperature of the heating probe 5 and the fourth temperature measuring probe 4 affected by the xylem sap flow, ΔTM It is an important parameter of Granier's original formula. Granier defines Δ TM is the temperature difference (℃) when the liquid flow density is 0 cm / s. There is no unified standard to define zero liquid flow (Δ TM ) condition, the most commonly used method in related research is: take 1 day as the time step, select the maximum temperature difference before dawn every day, and define it as Δ TM , in summary, Δ TM and Δ T They are respectively sap-free flow and xylem positive sap flow (F d >0) under the temperature difference between the two probes (the heating temperature of the heating probe 5 and the fourth temperature measuring probe 4).

[0075] It should be noted that the present invention can use any of the above two methods to calculate the liquid flow density. The monitoring data of the thermal diffusion method can be calculated to obtain a set of liquid flow density. The monitoring data of the thermal field deformation method can also be calculated to obtain a set of liquid flow density, which is equivalent to obtaining two sets of liquid flows calculated by the two methods at the xylem where the combined probe is installed. The advantages of this combined design of the present invention are as follows: 1) saving research costs, improving research efficiency, and reducing data errors. First of all, both methods are mainstream technologies in tree sap flow monitoring technology. Users can use a set of combined probes to conduct comparative studies of the two methods, and due to their combined characteristics, the errors caused by the radial and circumferential liquid flow and installation position of the tree in such comparative experiments can be minimized, thereby improving the accuracy of the experimental results. 2) The liquid flow density obtained by the two methods is different, and the combined probe can combine the advantages of the two. Although the liquid flow change trends measured by the two methods are consistent, due to the difference between the principle and configuration of the thermal field deformation method (three temperature measuring probes) and the thermal diffusion method (only one temperature measuring probe), the subtle changes in the xylem liquid flow can be monitored, and its measurement accuracy is higher than that of the thermal diffusion probe. Numerous studies have shown that the thermal diffusion method may cause large errors in the estimation of tree sap flow during installation, monitoring, and calculation. However, this method is currently the most widely used sap flow monitoring method. In this invention, the thermal diffusion probe is also optimized by adding radial measurement sites. The two groups of sap flow density obtained by the two methods in the combined probe can be used as reference objects for each other. The corresponding sap flow density calculation method can be selected according to actual application, and there is no restriction here.

[0076] Furthermore, the dual-mode forest sap flow measurement technology based on the thermal field deformation method and the thermal diffusion method monitors the trunk sap flow in the continuous heating mode, and the data collection interval can be 10 minutes, which is taken as an example but not limited to this.

[0077] Furthermore, the collected real-time data can be displayed in the data display module of the supporting local communication software (i-Logger), stored on the SD card at a fixed frequency, and uploaded to the cloud server platform through the GPRS module, so that researchers can remotely query the monitoring data, observe the changes in trunk sap flow, and analyze the characteristics of trunk sap flow.

[0078] Each embodiment in this specification is described in a progressive manner, and the same and similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In the description of this specification, the description of reference terms "a preferred embodiment", "further", "specifically", "in the present embodiment", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of this specification. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples without contradiction.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A liquid flow measurement device based on HFD and TDP dual modes, characterized in that: The device includes: A sensing component, comprising a first temperature measuring probe, a second temperature measuring probe, a third temperature measuring probe and a fourth temperature measuring probe arranged in a tree trunk, wherein the first temperature measuring probe, the second temperature measuring probe, the third temperature measuring probe and the fourth temperature measuring probe are arranged in sequence from top to bottom along the extension direction of the tree trunk, and the first temperature measuring probe, the second temperature measuring probe, the third temperature measuring probe and the fourth temperature measuring probe are arranged at non-equidistant intervals from top to bottom along the extension direction of the tree trunk, wherein the first temperature measuring probe and the third temperature measuring probe are symmetrically arranged based on a heating probe; A heating device, comprising a heating probe disposed in a tree trunk, wherein the heating probe and the second temperature measuring probe are located at the same height of the tree trunk; The data acquisition controller is used to control each temperature measuring probe of the sensing assembly to collect temperature data and control the heating probe to heat. Each temperature measuring probe in the sensing assembly adopts a T-type thermistor wire, and each of the temperature measuring probes includes a plurality of T-type thermocouple wires for multi-point measurement. The total length of each temperature measuring probe is N=x+(n-1)*i, where x is the distance between the innermost measuring point and the needle seat, n is the distance between each micro-thermocouple, and i is the number of thermocouples. HFD measurement is to collect the "symmetrical point temperature difference", i.e. the temperature difference between the first temperature measuring probe and the third temperature measuring probe, and the "asymmetrical point temperature difference", i.e. the temperature difference between the second temperature measuring probe and the third temperature measuring probe, so as to calculate the liquid flow density; The TDP measurement is performed by measuring the temperature difference between the heating temperature set by the heating probe and the temperature measured by the fourth temperature measuring probe.

2. The liquid flow measurement device based on HFD and TDP dual modes according to claim 1, characterized in that: The longitudinal spacing between the first temperature measuring probe, the heating probe and the third temperature measuring probe is 15 mm; the transverse spacing between the heating probe and the second temperature measuring probe is 5 mm; and the longitudinal spacing between the third temperature measuring probe and the fourth temperature measuring probe is 25 mm.

3. The liquid flow measurement device based on HFD and TDP dual modes according to claim 1, characterized in that: A heating resistor is arranged in the heating probe. The heating resistor adopts resistance wire of various materials, including constantan wire, tungsten wire, chromium wire or nickel wire. The heating power of the heating resistor is 0.06~0.08 w / cm, and the actual length of the heating resistor is consistent with the required resistivity of the probe.

4. The liquid flow measurement device based on HFD and TDP dual modes according to claim 3, characterized in that: Each of the probes comprises a slender probe body, and the heating resistor is arranged along the length direction of the probe body.

5. A measurement method of a liquid flow measurement device based on HFD and TDP dual modes according to any one of claims 1 to 4, characterized in that: include: Determine the location of the sensor components and heating devices for the tree species; Install the sensor assembly and the heating device at the installation location selected by the tree species; A constant voltage is applied to the forest tree species through the heating device to continuously supply heat. When the thermal equilibrium state, i.e. the steady state, is finally reached, the liquid flow density is calculated based on the temperature difference between the probes.

6. The measuring method according to claim 5, characterized in that: Calculation of liquid flux density based on the temperature difference between probes based on thermal field deformation method q s : In the formula, D is the thermal diffusivity of wood, K The "asymmetric point temperature difference" when the liquid flow is zero, dT as is the temperature difference between the second temperature measuring probe and the third temperature measuring probe, dT sym is the "symmetric point temperature difference", i.e. the temperature difference between the first temperature measuring probe and the third temperature measuring probe; Z ax is the distance between the heating probe and the first and third temperature measuring probes, Z tg is the distance between the heating probe and the second temperature measuring probe, L sw is the sapwood thickness of the measured plant.

7. The measuring method according to claim 5, characterized in that: Calculation of liquid flux density based on the temperature difference between probes based on the thermal diffusion method F d : In the formula, K is the temperature difference coefficient, K =(Δ TM -Δ T ) / Δ T , Δ TM The temperature difference between the heating temperature set for the heating probe and the fourth temperature measuring probe when the liquid flux density is 0 cm / s; Δ T the instantaneous temperature difference between the heating temperature set for the heating probe at a certain moment and the fourth temperature measuring probe; a and b are the coefficients of Granier original formula respectively.

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